Tools of the above type are oftenly used for breaking and rock drilling purposes and develop a high impact power to effectively carry out the intended work. However, high impact power also means that the tool housing as well as the components of the impact mechanism are subjected to severe strain during operation, and that the entire tool has to be of a rugged design. This means in turn that the tool tends to be rather large in size and heavy, which is a drawback when used in hand held applications.
Another reason why prior art tools of this kind tend to be rather heavy and bulky is that the housings comprise two or more parts which are held together by heavy duty screw joints, for instance in the form of lateral tie bolts. See SE 424522, EP 150170 and U.S. Pat. No. 2,558,165.
Some common types of prior art impact tools comprise housings in which the cylinder bore has a damping shoulder formed by a decreased diameter portion in the housing. This arrangement requires a rather complicated and costly working of the cylinder bore. An example of such a tool design is shown in EP 150170.
To avoid the above costly working requirement concerning the tool housing it has been previously suggested to form the tool housing with a constant diameter cylinder bore. See U.S. Pat. No. 2,558,165, 3,847,232, and 4,308,926. However, the impact tools shown in these patents still include heavy duty type threaded joints for the assemblage of tool housing parts and for mounting of separate working implement retainers and handles.